The invention relates to an apparatus for shaping workpieces that are generally are panels, sheet metal, foil or sheeting, which are disposed in such a manner between two tools, that a part to be shaped is not covered by the tools. After the workpieces are fixed, shaping work, such as bending work, is carried with a third tool.
Apparatuses are known which carry out shaping work (bending work) on workpieces which are clamped between two working panels. The clamping usually is mechanical, for example, by G clamps or cheek plates, which are disposed so that they can be moved hydraulically towards one another. The shaping, which is to be brought about by the bending work, generally is carried out by dies or bottom dies. Likewise, for the shaping of less complex formations, as required for profiles or chamfers, so-called "free bending" is carried out. Free bending, however, permits only a limited degree of complexity. An apparatus for carrying out such a method is known from the German patent 40 09 466. The method described there offers the possibility, after a particular adjustment of the tool, of producing a particular type of corner using a particular sheet metal. The pre-setting of the tool must be taken into consideration already when the tool is manufactured, since later modifications, which may be required for other workpieces (workpiece thickness, edge height, characteristic values of the material), cannot be carried out.
Moreover, this patent discloses an apparatus for bending and profiling corners, a tool for holding down the workpiece being used to lock the workpieces in position. The basic shape of this holding-down device is rectangular, so that it covers completely the region of the corner of the workpiece. However, due to the complete coverage of the corner region, stretching of the material in this region is prevented, so that cracks, which are not acceptable for esthetic as well as safety reasons, can develop in the comer region.